Occlusion Bypassing Apparatuses and Methods for Bypassing an Occlusion in a Blood Vessel

ABSTRACT

Occlusion bypassing apparatuses are disclosed for re-entering the true lumen of a vessel after subintimally bypassing an occlusion in a vessel. The occlusion bypassing apparatuses include a shaft component and a needle component slidably disposed within the shaft component and having an angled configuration when deployed. In embodiments hereof, the needle component has an angled distal tip segment that may be utilized to selectively bend a flexible distal portion of the shaft component in order to extend the flexible distal portion towards the true lumen of the vessel. The needle component is distally advanced relative to the shaft component to pierce through the intima of the vessel and thereafter enter the true lumen.

FIELD OF THE INVENTION

The invention relates generally to occlusion bypassing apparatuses andmethods of using such apparatus for subintimally bypassing a blockage ina blood vessel, such as a chronic total occlusion, and reentering thetrue lumen of the blood vessel distal of the blockage.

BACKGROUND OF THE INVENTION

Cardiovascular disease, including atherosclerosis, is the leading causeof death in the United States. One method for treating atherosclerosisand other forms of arterial lumen narrowing is percutaneous transluminalangioplasty, commonly referred to as “angioplasty” or “PTA,” or “PTCA”when performed in the coronary arteries. The objective in angioplasty isto restore adequate blood flow through the affected artery, which may beaccomplished by inflating a balloon of a balloon catheter within thenarrowed lumen of the artery to dilate the vessel.

The anatomy of arteries varies widely from patient to patient. Oftenpatient's arteries are irregularly shaped, highly tortuous and verynarrow. The tortuous configuration of the arteries may presentdifficulties to a clinician in advancement of the balloon catheter to atreatment site. In addition, in some instances, the extent to which thelumen is narrowed at the treatment site is so severe that the lumen iscompletely or nearly completely obstructed, which may be described as atotal occlusion. Total or near-total occlusions in arteries can preventall or nearly all of the blood flow through the affected arteries. Ifthe total or near total occlusion has been established for a long periodof time, the lesion may be referred to as a chronic total occlusion orCTO. Chronic total occlusions can occur in coronary as well asperipheral arteries. Chronic total occlusions are often characterized byextensive plaque formation and typically include a fibrous capsurrounding softer plaque material. This fibrous cap may present asurface that is difficult to penetrate with a conventional medicalguidewire.

A number of devices have been developed and/or used for the percutaneousinterventional treatment of CTOs, such as stiffer guidewires,low-profile balloons, laser light emitting wires, atherectomy devices,drills, drug eluting stents, and re-entry catheters. The factor that ismost determinative of whether the physician can successfully recanalizea CTO is the physician's ability to advance a suitable guidewire from aposition within the true lumen of the artery proximal to the CTO lesion,across the CTO lesion, i.e., either through the lesion or around it, andthen back into the true lumen of the artery at a location distal to theCTO lesion.

In some cases, such as where the artery is totally occluded by hard,calcified atherosclerotic plaque, the guidewire may tend to deviate toone side and penetrate through the intima of the artery, therebycreating a neo-lumen called a “subintimal tract,” i.e., a penetrationtract formed within the wall of the artery between the intima andadventitia. In these cases, the distal end of the guidewire may beadvanced to a position distal to the lesion but remains trapped withinthe subintimal tract. In such instances, it is then necessary to director steer the guidewire from the subintimal tract back into the truelumen of the artery at a location distal to the CTO lesion. The processof manipulating the guidewire to reenter the artery lumen is oftendifficult and various solutions have been proposed utilizing means forhandling such a reentry operation.

As well a number of catheter-based devices have been heretoforesuggested for redirecting subintimally placed guidewires or othermedical devices back into the true lumen of the artery. Included amongthese are a variety of catheters having laterally deployable cannulae,i.e., hollow needles. For example, the PIONEER® catheter system byMedtronic, Inc. utilizes a penetrator or needle that exits through aside exit port of the catheter to puncture the intimal layer distal ofthe CTO to re-enter the true lumen of the vessel. A second guidewire isthen passed through the laterally deployed needle and is advanced intothe true lumen of the artery. However, a need in the art still existsfor other medical devices or systems that consistently and reliablydirect guidewires or other devices tracked within the subintimal spaceof a vessel back into the true lumen of the vessel for the treatment ofa CTO.

BRIEF SUMMARY OF THE INVENTION

Embodiments hereof are directed to apparatuses for bypassing anocclusion in a blood vessel. In an embodiment, the apparatus includes ashaft component defining a lumen that extends from a proximal end to adistal end thereof and having a distal tip portion that is bendablerelative to a proximal portion thereof and a needle component configuredto be slidably disposed within the shaft component lumen and removabletherefrom. The needle component includes a proximal segment and anangled distal tip segment, wherein in a first configuration of theapparatus the angled distal tip segment of the needle component is heldin a straightened form within the shaft component and wherein in asecond configuration the angled distal tip segment of the needlecomponent bends the distal tip portion of the shaft component away froma longitudinal axis of the proximal portion. In embodiments hereof, aballoon is mounted on a distal portion of the shaft component and isutilized to anchor and stabilize the occlusion bypassing apparatuswithin a subintimal tract of a vessel.

In another embodiment, the apparatus includes an outer shaft component,an inner shaft component and a needle component. The outer shaftcomponent defines a lumen that extends from a proximal end to a distalend thereof and has a balloon mounted on a distal portion thereof. Theinner shaft component is configured to be slidably and rotatablydisposed within the outer shaft component lumen and removable therefrom,and the inner shaft component defines a lumen that extends from aproximal end to a distal end thereof. The needle component is configuredto be slidably disposed within the inner shaft component lumen andremovable therefrom, the needle component having a proximal segment andan angled distal tip segment. In a first configuration of the apparatus,the angled distal tip segment of the needle component is held in astraightened form within the inner and outer shaft components. In asecond configuration of the apparatus, when a distal portion of theinner shaft component extends from the distal end of the outer shaftcomponent with at least a portion of the angled distal tip segment ofthe needle component concurrently disposed therein, the angled distaltip segment of the needle component bends the distal portion of theinner shaft component away from a longitudinal axis of the apparatus.

Embodiments hereof also relate to methods for bypassing an occlusion ina blood vessel having a subintimal tract formed in a wall of the vesseladjacent to the occlusion. In one such method, a guidewire is advancedthrough the subintimal tract from a near or proximal side of theocclusion to a position where a distal end of the guidewire ispositioned in the subintimal tract on a far or distal side of theocclusion. A balloon catheter is advanced through the subintimal tractover the guidewire until a distal portion of the catheter is disposed atthe distal side of the occlusion. Once so positioned a balloon of theballoon catheter is inflated to anchor the balloon catheter within thesubintimal tract. An elongate needle component is advanced in astraightened configuration relative to the balloon catheter until adistal tip segment of the needle component extends from a distal end ofthe balloon catheter. Thereafter, the needle component is permitted toreturn to an angled configuration in which the distal tip segment bendsaway from a longitudinal axis of a proximal portion of the needlecomponent, wherein at least the distal tip segment of the needlecomponent has a shape memory to return the needle component to theangled configuration. In an embodiment, the needle component is held inthe straightened configuration by an elongate stylet that extendstherethrough. In another embodiment, the needle component is held in thestraightened configuration by a reinforced segment of the shaftcomponent.

In another embodiment for bypassing an occlusion in a blood vesselhaving a subintimal tract formed in a wall of the vessel adjacent to theocclusion, an outer shaft component of an occlusion bypassing apparatusis advanced over an indwelling guidewire until a distal portion of theouter shaft component is disposed at the distal side of the occlusion.An inner shaft component and a needle component of the occlusionbypassing apparatus are loaded within the outer shaft component until adistal portion of the inner shaft component is disposed within thedistal portion of the outer shaft component, wherein the needlecomponent is slidably disposed within the inner shaft component in astraight configuration. A balloon mounted on the occlusion bypassingapparatus is then inflated to anchor the occlusion bypassing apparatuswithin the subintimal tract. The needle component of the occlusionbypassing apparatus is advanced relative to the inner shaft componentuntil at least a portion of an angled distal tip segment of the needlecomponent is disposed within the distal portion of the inner shaftcomponent that extends from a distal end of the outer shaft component tothereby bend the distal portion of the inner shaft component away from alongitudinal axis of the occlusion bypassing apparatus.

In another embodiment for bypassing an occlusion in a blood vesselhaving a subintimal tract formed in a wall of the vessel adjacent to theocclusion, an occlusion bypassing apparatus having a shaft component anda needle component is advanced through the subintimal tract over anindwelling guidewire until a distal end of the occlusion bypassingapparatus is disposed at the distal side of the occlusion. The needlecomponent is slidably disposed within the shaft component and defines alumen through which the guidewire extends. A balloon of the occlusionbypassing apparatus is inflated to anchor the occlusion bypassingapparatus within the subintimal tract. The needle component of theocclusion bypassing apparatus is advanced relative to the shaftcomponent until at least a portion of an angled distal tip segment ofthe needle component is disposed within a distal portion of the shaftcomponent to thereby bend the distal portion of the shaft component awayfrom a longitudinal axis of the occlusion bypassing apparatus.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following description of embodiments hereof asillustrated in the accompanying drawings. The accompanying drawings,which are incorporated herein and form a part of the specification,further serve to explain the principles of the invention and to enable aperson skilled in the pertinent art to make and use the invention. Thedrawings are not to scale.

FIG. 1 is a side view of an occlusion bypassing apparatus according toan embodiment hereof, wherein configuration a distal end of an outershaft component is shown in partial section.

FIG. 1A is a cross-sectional view of the occlusion bypassing apparatusof FIG. 1 taken along line A-A thereof.

FIG. IAA is a cross-sectional view of an occlusion bypassing apparatusof FIG. 1 taken along line A-A thereof depicting an outer shaftcomponent in accordance with another embodiment hereof.

FIG. 2 is a side view of a distal portion of the occlusion bypassingapparatus of FIG. 1, wherein a distal portion of an inner shaftcomponent of the apparatus is in a bent configuration.

FIG. 2A depicts a balloon having an asymmetrical inflated configurationin accordance with another embodiment hereof

FIG. 2B depicts a cross-sectional view of a shaft component thatutilizes balloons as shown in FIG. 2A in accordance with anotherembodiment hereof.

FIG. 3 is a side view of the distal portion of the occlusion bypassingapparatus shown in FIG. 2, wherein a needle component of the apparatusextends from the inner shaft component.

FIG. 4A is a side view of an outer shaft component of the occlusionbypassing apparatus of FIG. 1 in accordance with an embodiment hereof.

FIG. 4B is a side view of an inner shaft component of the occlusionbypassing apparatus of FIG. 1 in accordance with an embodiment hereof.

FIG. 4BB is a cross-sectional view of the inner shaft component of FIG.4B taken along line BB-BB thereof.

FIG. 4C is a side view of a needle component of the occlusion bypassingapparatus of FIG. 1 in accordance with an embodiment hereof

FIG. 4D is a side view of an alternative embodiment of an inner shaftcomponent of the occlusion bypassing apparatus of FIG. 1.

FIG. 5 is a side view of an occlusion bypassing apparatus according toanother embodiment hereof.

FIG. 6 is a side view of a needle component of the occlusion bypassingapparatus of FIG. 5 in accordance with an embodiment hereof

FIG. 7 is a side view of a stiffening stylet of the occlusion bypassingapparatus of FIG. 5 in accordance with an embodiment hereof

FIG. 8A is a side view of a subassembly of the needle component andstylet of FIGS. 6 and 7 with the stylet fully inserted to extend throughthe needle component such that the needle component is held in asubstantially straightened form by the stylet.

FIG. 8B is a side view of the subassembly in FIG. 8A with the styletpartially retracted from the needle component such that the needlecomponent is permitted to bend.

FIG. 8C is a side view of the needle component as shown in FIG. 8Areturned to its shape memory bent configuration after the stylet hasbeen removed.

FIG. 9 is a side view of an occlusion bypassing apparatus according toanother embodiment hereof.

FIG. 10 depicts a side view of a distal end of an occlusion bypassingapparatus in accordance with embodiments hereof with an exemplaryradiopaque marker attached thereto.

FIG. 10A is a perspective view of the exemplary radiopaque marker shownin FIG. 10.

FIG. 11 is a perspective view of a metallic shaft segment in accordancewith an embodiment hereof.

FIG. 12 is a diagram of an artery showing the three layers of tissuethat comprise the artery wall.

FIGS. 13-23 illustrate the steps of utilizing the occlusion bypassingapparatus of FIG. 1 to bypass a chronic total occlusion according to anembodiment hereof.

FIGS. 24-29 illustrate the steps of utilizing the occlusion bypassingapparatus of FIG. 1 to bypass a chronic total occlusion according toanother embodiment hereof.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present invention are now described withreference to the figures, wherein like reference numbers indicateidentical or functionally similar elements. The terms “distal” and“proximal” are used in the following description with respect to aposition or direction relative to the treating clinician. “Distal” or“distally” are a position distant from or in a direction away from theclinician. “Proximal” and “proximally” are a position near or in adirection toward the clinician. The term “shape memory” is used in thefollowing description with reference to the needle components hereof andis intended to convey that the structures are shaped or formed from amaterial that can be provided with a mechanical memory to return thestructure from a straightened delivery configuration to an angled orbent deployed configuration. Non-exhaustive exemplary materials that maybe imparted with a shape memory include stainless steel, apseudo-elastic metal such as a nickel titanium alloy or nitinol, or aso-called super alloy, which may have a base metal of nickel, cobalt,chromium, or other metal. Shape memory may be imparted to a tubular orrod-like structure by thermal treatment to achieve a spring temper instainless steel, for example, or to set a mechanical memory in asusceptible metal alloy, such as nitinol.

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Although the description of the invention is in the contextof treatment of blood vessels such as smaller diameter peripheral orcoronary arteries, the invention may also be used in any other bodypassageways where it is deemed useful. Although the description of theinvention generally refers to a system and method of bypassing a vesselblockage in a proximal-to-distal direction, i.e. antegrade or with theblood flow, the invention may be used equally well to bypass a vesselblockage in a distal-to-proximal direction, i.e. retrograde or againstthe blood flow if access is available from that direction. In otherterms, the system and method described herein may be considered tobypass a vessel blockage from a near side of the blockage to a far sideof the blockage. Furthermore, there is no intention to be bound by anyexpressed or implied theory presented in the preceding technical field,background, brief summary or the following detailed description.

Embodiments hereof relate to a system and method for re-entering thetrue lumen of a vessel after subintimally bypassing an occlusion in ablood vessel such as a chronic total occlusion (CTO) of an artery. FIG.1 illustrates the main components of occlusion bypassing apparatus 100,which are separately shown in FIGS. 4A-4C, assembled one within theother with a distal portion 124 of an inner shaft component 114extending from a distal end 106 of an outer shaft component 102. Moreparticularly with reference to FIGS. 1 and 4A-4C, an occlusion bypassingapparatus 100 includes an outer shaft component 102 with a balloon 112for stabilization or anchoring the occlusion bypassing apparatus, aninner shaft component 114 slidably and rotatably disposed within outershaft component 102, and a needle component 130 disposed within innershaft component 114. Needle component 130 is utilized to selectivelybend or curve distal portion 124 of inner shaft component 114, as shownin FIGS. 2 and 3, in order to position or extend distal portion 124 ofinner shaft component 114 towards the true lumen of a vessel, as will beexplained in more detail herein. While occlusion bypassing apparatus 100is stabilized within a subintimal space of a vessel, needle component130 is advanced to bend or bow distal portion 124 of inner shaftcomponent 114, and thereafter, if required, needle component 130 andinner shaft component 114 may be jointly or collectively rotated toorient a distal opening 126 of inner shaft component distal portion 124towards the true lumen of the vessel. Needle component 130 also providesthe required stiffness to occlusion bypassing apparatus 100 forre-entering the true lumen of the vessel. In FIG. 2 a distal tip 136 ofneedle component 130, which is visible in FIGS. 3 and 4C, is disposedwithin and bends distal portion 124 of inner shaft component 114 in aconfiguration suitable for rotation of the two components within thesubintimal space of the vessel wall. In FIG. 3 distal tip 136 is exposedto distally extend from distal opening 126 of inner shaft component 114in a configuration that is suitable for puncturing the vessel wall togain access to the true lumen.

With reference to FIGS. 1, 1A and 4A-4C, outer shaft component 102 is anelongate tubular or cylindrical element defining a lumen 108 thatextends from a proximal end 104 to a distal end 106 thereof and hasballoon 112 mounted on a distal portion thereof. In an embodiment, outershaft component may be sized to be used with a 5F introducer sheath withlumen 108 being sized to accommodate a guidewire having an outerdiameter of 0.035 inch. Proximal end 104 of outer shaft component 102extends out of the patient and is coupled to a first hub 152. Aninflation shaft or tube 148 defining an inflation lumen 150 extendsthrough lumen 108 of outer shaft component 102 to allow inflation fluidreceived through Luer fitting 154 of first hub 152 to be delivered toballoon 112. FIG. IAA is a cross-sectional view of an occlusionbypassing apparatus of FIG. 1 taken along line A-A thereof depicting anouter shaft component 102AA in accordance with another embodimenthereof, wherein the outer shaft component 102AA includes an inflationshaft or tube 148AA defining an inflation lumen 150AA that is attachedto extend along an outer surface of outer shaft component 102AA to allowinflation fluid received through Luer fitting 154 of first hub 152 to bedelivered to balloon 112. In accordance with an embodiment hereof, thecombined structures of outer shaft component 102, balloon 112 and hub152 as described herein may be considered to comprise a ballooncatheter. It would also be understood by one of ordinary skill in theart of balloon catheter design that hub 152 includes a proximal port 156with a hemostatic valve to accommodate insertion of other components ofocclusion bypassing apparatus 100 into outer shaft component 102, andthat Luer fitting 154, or some other type of fitting, may be connectedto a source of inflation fluid (not shown) and may be of anotherconstruction or configuration without departing from the scope of thepresent invention. Other types of construction are also suitable forouter shaft component 102, such as, without limitation thereto, acatheter shaft having a central lumen and an inflation lumen formed bymulti-lumen profile extrusion. When inflated, balloon 112 anchorsocclusion bypassing apparatus 100 within the anatomy, more particularlywithin the subintimal space of the vessel wall when utilized in thetreatment of a CTO, so as to provide stability thereto.

Outer shaft component 102 and inflation shaft 148 may be formed ofpolymeric materials, non-exhaustive examples of which includepolyethylene terephthalate (PET), polypropylene, polyethylene, polyetherblock amide copolymer (PEBA), polyamide, fluoropolymers, and/orcombinations thereof, either laminated, blended or co-extruded.Optionally, outer shaft component 102 or some portion thereof may beformed as a composite having a reinforcement layer incorporated within apolymeric body in order to enhance strength and/or flexibility. Suitablereinforcement layers include braiding, wire mesh layers, embedded axialwires, embedded helical or circumferential wires, hypotubes, and thelike. In one embodiment, for example, at least a proximal portion ofouter shaft component 102 may be formed from a reinforced polymerictube. In accordance with an embodiment hereof, balloon 112 may radiallyinflate uniformly so as to have a symmetric expanded configuration aboutthe longitudinal axis L_(A) of occlusion bypassing apparatus 100, asshown in FIGS. 2 and 3. In accordance with another embodiment hereof,balloons 212 a, 212 b having an asymmetric expanded configurationrelative to the longitudinal axis L_(A) of occlusion bypassing apparatus100 may be used for anchoring and stabilizing the apparatus within thesubintimal space, as shown in FIG. 2A. With reference to the dualballoon arrangement depicted in FIG. 2B, balloons 212 a, 212 b primarilyexpand in opposite directions to each other along an axis T_(A)transverse to the longitudinal axis L_(A) of occlusion bypassingapparatus 100 to thereby provide a flatter somewhat oval cross-sectionto the apparatus when inflated. In accordance with embodiments hereof,balloons 112, 212 a, 212 b may be formed of any suitable polymericmaterial used for dilatation balloon manufacturing, for instance,polyether block amide (PEBA) and polyurethane (PU), and may have anouter diameter in the range of 2-4 mm and a length in the range of 5-15mm.

Inner shaft component 114 is an elongate tubular or cylindrical elementthat is configured to be slidably and rotatably disposed within lumen108 of outer shaft component 102 and removable therefrom. As usedherein, “slidably” denotes back and forth movement in a longitudinaldirection while “rotatably” denotes movement or rotation about alongitudinal axis L_(A) of the occlusion bypassing apparatus 100. Asbest shown in FIG. 4B, in one embodiment hereof, inner shaft component114 includes a first or proximal portion 122, a second or distal portion124, and a reinforced intermediate portion 128 disposed or sandwichedbetween proximal and distal portions 122, 124. Distal portion 124 ofinner shaft component 114 may include a radiopaque marker 110 coupledthereto in order to visually monitor the position thereof. Proximalportion 122, intermediate portion 128, and distal portion 124collectively define a continuous lumen 120 that extends from a proximalend 116 to a distal end 118 of inner shaft component 114. Lumen 120extends substantially the entire length of the catheter foraccommodating needle component 130. Proximal end 116 of inner shaftcomponent 114 is coupled to a second hub 160 having a proximal port 162with a hemostatic valve, and is disposed within strain relief element158 that is attached to distally extend from second hub 160.

In accordance with embodiments hereof, proximal portion 122 is a tubularor cylindrical shaft segment having a first flexibility, distal portion124 is a tubular or cylindrical shaft segment having a secondflexibility, and intermediate portion 128 is a tubular or cylindricalshaft segment having a third flexibility with intermediate portion 128being less flexible or stiffer than proximal and distal portions 122,124. In the embodiment shown in FIGS. 4B and 4BB, proximal portion 122is an elongate polymeric tube having a reinforcement layer, distalportion 124 is a polymeric tube that is more flexible than the proximalportion, and intermediate portion 128 includes a metallic shaft segment127, such as a short length of a metallic hypotube, having a proximalhalf 127 a embedded within a distal end of proximal portion 122 and adistal half 127 b overlapped by a proximal end of distal portion 124. Inother words, intermediate portion 128 of the embodiment of FIG. 4Bincludes the metallic shaft segment 127 and segments of proximal anddistal portions 122, 124 that overlap therewith.

Proximal and distal portions 122, 124 may be formed from any suitablepolymeric material for forming a medical device, such as polyethyleneterephthalate (PET), polypropylene, polyamide, polyethylene, polyetherblock amide (PEBA), fluoropolymers such as polytetrafluoroethylene(PTFE) or fluorinated ethylene propylene (FEP), or combinations thereof,with the material for forming distal portion 124 being one that is moreflexible than the material of proximal portion 122 so that distalportion 124 may be readily bent or curved via needle component 130 asdescribed herein. In an embodiment, for example, the proximal and distalportions 122, 124 may both be formed from the same soft polymericmaterial, such as polyether block amide (PEBA) or a standard polyamidesuch as Nylon 12 or Nylon 66, with a reinforcing mesh, braid or wirelayer being incorporated within the polymeric material of proximalportion 122 in order to enhance the column strength thereof. In anotherembodiment, proximal portion 122 and distal portion 124 may be formedfrom different polymeric materials having different flexibilities withproximal portion 122 being formed from a first material, such asstainless steel braid embedded in PEBAX® 7233, and distal portion 124being formed from a second material, such as PEBAX® 5533, that is moreflexible than the first material. In accordance with embodiments hereof,reinforced intermediate portion 128 may be formed by embedding metallicshaft segment 127, for e.g., of stainless steel or nitinol, within thepolymeric material of one of the proximal and distal portions of theinner shaft component 114. In an embodiment, proximal half 127 a ofmetallic shaft segment 127 may be glued to or embedded in proximalportion 122 with distal half 127 b of metallic shaft segment 127 beingfit within distal portion 124.

FIG. 4D illustrates another embodiment of an inner shaft component 114Athat may be used instead of inner shaft component 114 in the occlusionbypassing apparatus 100 of FIG. 1. Inner shaft component 114A includes afirst or proximal portion 122A and a second or distal portion 124A.Proximal portion 122A and distal portion 124A collectively define acontinuous lumen (not shown) that extends from a proximal end 116A to adistal end 118A of inner shaft component 114A. In this embodiment, innershaft component 114A is a continuous metallic hypotube. Distal portion124A includes a spiral cut segment 125A so that distal portion 124A ismore flexible than proximal portion 122A. The spiral cut or slit througha sidewall of distal portion 124A increases the flexibility thereof sothat distal portion 124A may be readily bent or curved via needlecomponent 130 as will be described in more detail herein.

Needle component 130 is an elongate tubular or cylindrical element thatis configured to be slidably disposed within lumen 120 of inner shaftcomponent 114 and removable therefrom. More particularly, needlecomponent 130 is disposed within inner shaft component 114 such thatthere is sufficient space or room therebetween for needle component 130to be moved or slidable in a longitudinal direction relative to innershaft component 114. In other words, there is not a tight interferenceor friction fit between needle component 130 and inner shaft component114. However, needle component 130 is disposed within inner shaftcomponent 114 such that inner shaft component 114 rotates or spins withrotation of needle component 130. In other words, when needle component130 is rotated by a clinician, needle component 130 contacts an innersurface of inner shaft component 114 and thereby rotates inner shaftcomponent 114. The two components may rotate simultaneously as anensemble structure, or they may rotate independently. In an embodiment,a removable locking device or wire torquer may be utilized at theproximal ends of the needle and inner shaft components during rotationthereof, wherein the locking device or wire torquer may then be removedwhen the needle component is required to be moved relative to the innershaft component in a longitudinal direction.

In order to accommodate a guidewire, needle component 130 may be ahypotube that defines a lumen 138 therethrough from a proximal end 132to a distal end 134 of the needle component. Proximal end 132 extendsout of the patient from second hub 160 to be manipulated by a clinicianand distal end 134 includes a distal tip 136 configured to pierce orpenetrate through a wall of a vessel. In an embodiment, lumen 138 ofneedle component 130 is sized to accommodate a guidewire having an outerdiameter equal to or less than 0.014 inch such that occlusion bypassingapparatus 100 has a low profile.

As best shown in FIG. 4C, needle component 130 has an elongated first orproximal segment 140 and a second or distal angled tip segment 142 so asto have an angled or bent configuration. More particularly, as shown inFIG. 4C, angled distal tip segment 142 extends, bends, or otherwisecurves at an acute angle Θ relative to a longitudinal axis of elongatedproximal segment 140 and in turn relative to the longitudinal axis L_(A)of occlusion bypassing apparatus 100. In embodiments hereof, angle Θ maybe in the range of 30° to 80°. In an embodiment at least angled distaltip segment 142 of needle component 130 is formed from a biocompatibleresilient metal such as spring temper stainless steel or nitinol, whichutilizes the elastic properties of stress induced martensite, such thata heat or thermal treatment of the selected material may be used to setthe shape memory of angled distal tip segment 142. In an embodiment,needle component 130 may be formed from more than one material, fore.g., with an elongated proximal segment 140 being formed of stainlesssteel and only angled distal tip segment 142 being formed of nitinol.

In a first configuration of occlusion bypassing apparatus 100 shown inFIG. 1, angled distal tip segment 142 of needle component 130 isrestrained or held in a straightened form within intermediate portion128 of inner shaft component 114, which is formed from a relativelystiff or less flexible material as described above in order toeffectively straighten the angled distal tip segment. In the firstconfiguration, flexible distal portion 124 of inner shaft component 114may distally extend from distal end 106 of outer shaft component 102, asshown in FIG. 1, or may be disposed within distal end 106 of outer shaftcomponent 102.

In a second configuration of occlusion bypassing apparatus 100 shown inFIG. 2, distal portion 124 of inner shaft component 114 distally extendsfrom distal end 106 of outer shaft component 102 and needle component130 is distally advanced relative to inner shaft component 114 such thatangled distal tip segment 142 is no longer constrained by intermediateportion 128 of inner shaft component 114. Balloon 112 may be expanded orinflated to anchor outer shaft component 102 within a subintimal tracteither before or after the distal advancement of needle component 130.When released from intermediate portion 128, angled distal tip segment142 resumes its shape memory geometry by its own internal restoringforces and concurrently bends, curves, or bows flexible distal portion124 of inner shaft component 114 away from the longitudinal axis L_(A)of occlusion bypassing apparatus 100 such that flexible distal portion124 of inner shaft component 114 extends at acute angle Θ relative tothe longitudinal axis L_(A) of occlusion bypassing apparatus 100, asshown in FIGS. 2 and 3. As described with respect to FIG. 4C, angle Θmay be in the range of 30° to 80°. Bending of distal portion 124 ofinner shaft component 114 permits a user or clinician to orient distalopening 126 of distal portion 124 of inner shaft component 114 towards atrue lumen of a vessel as described herein. The position of distalportion 124 of inner shaft component 114 during bending thereof may bemonitored via marker 110 thereon.

In another embodiment hereof, inner shaft component 114 of occlusionbypassing apparatus 100 does not include a reinforced intermediateportion 128 having a metallic shaft segment 127. In such an embodiment,the combination or subassembly of outer shaft component 102 and innershaft component 114 has a sufficient stiffness or rigidity to hold theangled distal tip segment 142 of needle component 130 in a straightenedposition when the angled distal tip segment 142 is concurrently disposedwithin both outer shaft component 102 and inner shaft component 114. Theangled distal tip segment 142 then resumes its bent shape, as shown inFIGS. 2 and 3, when flexible distal portion 124 of inner shaft component114 is distally extended relative to outer shaft component 102.

Distal tip 136 of needle component 130 is disposed within inner shaftcomponent 114, as shown in FIG. 2, during rotation of inner shaftcomponent 114 and needle component 130. Once distal opening 126 of innershaft component 114 is positioned in the direction of the true lumen ofthe vessel, distal tip 136 of needle component 130 is extended todistally protrude from distal opening 126 of inner shaft component 114,while distal tip segment 142 of needle component 130 still bends distalportion 124 of inner shaft component 114 away from longitudinal axisL_(A) of occlusion bypassing apparatus 100. When needle component 130 isdistally advanced or extended as shown in FIG. 3, distal tip 136 may beused to penetrate through the vessel wall and re-enter a true lumen of avessel as described herein.

FIG. 5 depicts an occlusion bypassing apparatus 500 in accordance withanother embodiment hereof. Occlusion bypassing apparatus 500 includes ashaft component 502 that defines a through lumen from a proximal end 504to a distal end 506 thereof through which a subassembly of a needlecomponent 530 and a stiffening stylet 531, shown unassembled in FIGS. 6and 7, are slidably and rotatably disposed. As well the through lumen ofshaft component 502 will accommodate a guidewire therethrough and maycontain a separate guidewire lumen. Shaft component 502 includes aproximal shaft portion 522 and a distal shaft portion 524 with a balloon512 being secured to extend from an outer surface thereof. Proximal end504 of shaft component 502 is coupled to a hub 552 that includes a Luerfitting 554 for delivering an inflation fluid to balloon 512 via aninflation lumen (not shown) of shaft component 502 and a proximal port556 for permitting insertion and manipulation of the needle component530 and stylet 531 subassembly therethrough. The combined structures ofshaft component 502, balloon 512 and hub 552 as described herein may beconsidered to comprise a balloon catheter in accordance with anembodiment hereof. One of ordinary skill in the art of balloon catheterdesign will appreciate that hub 552 may include another type of fittingthat may be connected to a source of inflation fluid (not shown) and maybe of another construction or configuration without departing from thescope of the present invention.

As similarly described with reference to formation of outer shaftcomponent 102 of the previous embodiment, proximal and distal shaftportions of shaft component 502 may be formed of polymeric materials,non-exhaustive examples of which include polyethylene terephthalate(PET), polypropylene, polyethylene, polyether block amide copolymer(PEBA), polyamide, fluoropolymers, and/or combinations thereof, eitherlaminated, blended or co-extruded. Optionally, shaft component 502 orsome portion thereof may be formed as a composite having a reinforcementlayer incorporated within a polymeric body in order to enhance strengthand/or flexibility. Suitable reinforcement layers include braiding, wiremesh layers, embedded axial wires, embedded helical or circumferentialwires, hypotubes, and the like. In one embodiment, for example, at leasta proximal portion of shaft component 502 may be formed from areinforced polymeric tube with distal shaft portion 524 being formed tohave or include an atraumatic tip 525 of occlusion bypassing apparatus500.

Needle component 530 is configured to be slidably and rotatably disposedwithin the lumen of shaft component 502 and defines a lumen that extendsfrom a proximal end 632 to a distal end 636 thereof for receiving stylet531 therein. Needle component 530 has an elongated first or proximalsegment 640 and a second or distal angled tip segment 642, as shown inFIG. 6. Angled distal tip segment 642 has a bent or curved configurationthat extends, bends, or otherwise curves at an acute angle Θ relative toelongated proximal segment 640 and relative to longitudinal axis L_(A)of occlusion bypassing apparatus 500. In embodiments hereof, angle Θ maybe in the range of 30° to 80°. Needle component proximal end 632proximally extends from hub proximal port 556 to be accessible by aclinician and needle component distal end 636 includes a tip configuredto pierce or penetrate through a wall of a vessel.

As similarly described with reference to formation of needle component130 of the previous embodiment, at least angled distal tip segment 642of needle component 530 is formed of a biocompatible resilient metalsuch as spring temper stainless steel or nitinol, which utilizes theelastic properties of stress induced martensite, such that a heat orthermal treatment of the selected material may be used to provide ashape set or shape memory to angled distal tip segment 642. In anembodiment, needle component 530 may be a hypotube of spring temperstainless steel or nitinol with a distal end that has been shape set inan angled configuration. In another embodiment, needle component 530 maybe formed from more than one material, e.g., with elongated proximalsegment 640 being formed of stainless steel and only angled distal tipsegment 642 being formed of nitinol to have a shape memory.

The lumen of needle component 530 is sized to slidably accommodatestylet 531 therein. With reference to FIGS. 7, and 8A-8C, stylet 531 isan elongate wire structure having a proximal end 733 and a distal end735 with a length and diameter that are sized to extend through needlecomponent 530 such that when stylet 531 is inserted therein angleddistal tip segment 642 is thereby straightened, as shown in FIG. 8A.When needle component 530 is held in a straightened configuration bystylet 531 as shown in FIG. 8A, the subassembly may be readily loadedwithin and distally advanced relative to shaft component 502. Inaddition, once the subassembly is loaded and fully advanced throughshaft component 502, needle component 530 may be distally advancedrelative to both stylet 531 and shaft component 502 to thereby in acontrolled manner gradually return distal tip segment 642 to its shapeset curved configuration. With reference to FIG. 8B, needle component530 is shown having been distally advanced relative to stylet 531 to apoint where distal tip segment 642 begins to bend, with stylet 531 stillextending therein. With reference to FIG. 8C, needle component 530 isshown after stylet 531 has been fully removed such that distal tipsegment 642 has fully returned to its shape set curved configuration.

FIG. 9 depicts an occlusion bypassing apparatus 900 in accordance withanother embodiment hereof. Occlusion bypassing apparatus 900 includes ashaft component 902 that defines a lumen from a proximal end 904 to adistal end 906 thereof through which a needle component, such aspreviously described needle component 530, is slidably and rotatablydisposed. Shaft component 902 includes a proximal shaft portion 922, areinforced intermediate shaft portion 928 and a distal shaft portion 924with a balloon 912 being secured to extend from an outer surface of theproximal shaft portion 922. Proximal end 904 of shaft component 902 iscoupled to a hub, such as previously described hub 552, that includes aLuer fitting for delivering an inflation fluid to balloon 912 via aninflation lumen (not shown) of shaft component 902 and a proximal portfor permitting insertion and manipulation of needle component 530therethrough, The combined structures of shaft component 902, balloon912 and hub 552 as described herein may be considered to comprise aballoon catheter in accordance with an embodiment hereof.

In the embodiment shown in FIG. 9, proximal shaft portion 922 is anelongate polymeric tube having a reinforcement layer, distal shaftportion 924 is a polymeric tube that is more flexible than the proximalshaft portion, and intermediate shaft portion 928 includes a shortmetallic shaft segment 927 having a proximal half 927 a embedded withina distal end of proximal shaft portion 922 and a distal half 927 boverlapped by a proximal end of distal shaft portion 924. Moreparticularly as similarly described with reference to the formation ofinner shaft component 114 of occlusion bypassing apparatus 100, proximaland distal shaft portions 922, 924 of shaft component 902 may be formedfrom any suitable polymeric material for forming a medical device, suchas polyethylene terephthalate (PET), polypropylene, polyamide,polyethylene, polyether block amide (PEBA), fluoropolymers such aspolytetrafluoroethylene (PTFE) or fluorinated ethylene propylene (FEP),or combinations thereof, with the material for forming distal shaftportion 924 being one that is more flexible than the material ofproximal shaft portion 922 so that distal shaft portion 924 forms anatraumatic tip 925 of occlusion bypassing apparatus 900 and so thatdistal shaft portion 924 may be readily bent or curved via needlecomponent 530 as described herein. In an embodiment, for example, theproximal and distal shaft portions 922, 924 may both be formed from thesame soft polymeric material, such as polyether block amide (PEBA) or astandard polyamide such as Nylon 12 or Nylon 66, with a reinforcingmetallic mesh, braid or wire layer being incorporated within thepolymeric material of proximal shaft portion 922 in order to enhance thecolumn strength thereof. In another embodiment, proximal shaft portion922 and distal shaft portion 924 may be formed from different polymericmaterials having different flexibilities with proximal shaft portion 922being formed from a first material, such as stainless steel braidembedded in PEBAX® 7233, and distal shaft portion 924 being formed froma second material, such as PEBAX® 5533, that is more flexible than thefirst material. In accordance with embodiments hereof, intermediateshaft portion 928 may be formed by embedding metallic shaft segment 927,e.g., of stainless steel or nitinol, within the polymeric material ofone of the proximal and distal portions of the shaft component 922. Inan embodiment, a proximal half 927 a of metallic shaft segment 927 maybe glued to or embedded in proximal shaft portion 922 with a distal half927 b of metallic shaft segment 927 being fit within distal shaftportion 924.

In FIG. 9 occlusion bypassing apparatus 900 is depicted with needlecomponent 530 loaded and in a straightened form within shaft component902 such that the apparatus as shown may be advanced over a guidewire toa treatment site. In an embodiment, the guidewire may be slidablyreceived through the lumen of needle component 530. More particularly,angled distal tip segment 642 of needle component 530 is restrained orheld in a straightened form within intermediate shaft portion 928 ofshaft component 902, which is formed from a relatively stiff or lessflexible material as described above in order to effectively straightenthe angled distal tip segment. Once occlusion bypassing apparatus 900has been tracked through the subintimal tract or space such that distaltip 925 is properly positioned at the treatment site, needle component530 is distally advanced relative to shaft component 902 such thatangled distal tip segment 642 is no longer constrained by intermediateshaft portion 928. Balloon 912 may be expanded or inflated to anchorshaft component 902 within the subintimal tract either before or afterthe distal advancement of needle component 530. When released fromintermediate shaft portion 928, angled distal tip segment 642 resumesits shape memory geometry by its own internal restoring forces andconcurrently bends, curves, or bows flexible distal shaft portion 924away from the longitudinal axis L_(A) of occlusion bypassing apparatus900 such that flexible distal shaft portion 924 extends at acute anglerelative to the longitudinal axis L_(A) of occlusion bypassing apparatus900, as similarly described with reference to inner shaft component 114of occlusion bypassing apparatus 100 shown in FIGS. 2 and 3. Bending ofdistal shaft portion 924 permits a user or clinician to orient anopening 926 at shaft component distal end 906 towards a true lumen of avessel as described herein.

In accordance with embodiments hereof during positioning of the distalopenings 126, 926 of occlusion bypassing apparatus 100, 900 such thatthe openings are directed toward the true lumen of a vessel, theposition of distal portion 124 of inner shaft component 114 of occlusionbypassing apparatus 100 and the position of distal shaft portion 924 ofshaft component 902 of occlusion bypassing apparatus 900 may include aradiopaque marker, such as radiopaque marker 1010 shown in FIGS. 10 and10A, to permit visualization thereof under fluoroscopic imagingtechniques. In alternate embodiments hereof to monitor the positioningof the distal openings 126, 926 of occlusion bypassing apparatus 100,900, a metallic shaft segment 1127 of FIG. 11 may be used withinembodiments hereof that include an intermediate portion 128 orintermediate shaft portion 928. Metallic shaft segment 1127 is of amaterial that may be visualized under fluoroscopic imaging techniquesand includes an orienting geometry, such as hemispherical protrusion1123, at a distal end 1129 thereof that may be used by the clinician toassure proper positioning.

FIG. 12 is a sectional view of the anatomy of an artery wall, which forpurposes of this description is shown to consist essentially of threelayers, the tunica intima I (“intima”), tunica media M (“media”) whichis the thickest layer of the wall, and the tunica adventitia A(“adventitia”). In some arteries an internal elastic membrane IEM isdisposed between the media M and adventitia A. The adventitia A is madeof collagen, vasa vasorum and nerve cells, the media M is made of smoothmuscle cells, and the intima I is made up of a single layer ofendothelial cells that provide a nonthrombogenic surface for flowingblood. An occlusion bypassing apparatus in accordance with embodimentshereof is used as part of a system for creating a subintimal reentryconduit within a wall of a blood vessel V to allow blood flow around anocclusion. FIGS. 13-23 illustrate an exemplary method of using theabove-described occlusion bypassing apparatus 100 to bypass a chronictotal occlusion (CTO) according to an embodiment hereof, but it would beunderstood by one of ordinary skill in the art that the depicted methodmay be adapted to be performed by other occlusion bypassing apparatusdisclosed herein. Although described in relation to bypassing a CTO, itshould be understood that the methods and apparatus described herein maybe used for bypassing any tight stenoses in arteries or other anatomicalconduits and are not limited to total occlusions.

As shown in FIG. 13, in accordance with techniques known in the field ofinterventional cardiology and/or interventional radiology, a firstguidewire 170 having a distal end 172 is transluminally advanced throughthe vasculature to a position upstream or proximal of a treatment site,which in this instance is shown as occlusion O within a lumen L of bloodvessel V. Guidewire 170 pierces the intima I and is advanced distally tocreate a subintimal tract by locally dissecting or delaminating intima Ifrom media M or by burrowing through media M. Guidewire 170 has arelatively larger outer diameter such as between 0.032-0.040 inches inorder to have sufficient column strength to gain access to thesubintimal space of vessel V. In order to pierce the intima I, aclinician may manipulate distal end 172 of guidewire 170 by prolapsingor bending-over the distal end of guidewire 170 (not shown) andthereafter may use the stiffer arc or loop of the prolapsed distal endto pierce into the intima I to advance guidewire 170 there through. Thepiercing of the intima I is aided by the fact that typically bloodvessel V is diseased, which in some instances makes the intima I proneto piercing. Guidewire 170 is distally advanced within the subintimaltract from a near or proximal side of occlusion O to a position wheredistal end 172 thereof is positioned in the subintimal tract on a far ordistal side of occlusion O.

Alternatively, another device other than guidewire 170 may be initiallyused to create the subintimal tract. Those of ordinary skill in the artwill appreciate and understand the types of alternative devices that maybe used in this step including an apparatus known as an “olive”, a laserwire, an elongate radiofrequency electrode, or any other device suitablefor boring or advancing through the vessel tissue. If an alternativedevice is used instead of guidewire 170 to form the subintimal tract,such alternative device may be removed and replaced with guidewire 170or a smaller diameter guidewire after the subintimal tract has beenformed.

After the subintimal tract is formed, outer shaft component 102 ofocclusion bypassing apparatus 100 is tracked over guidewire 170 andadvanced until distal end 106 of outer shaft component 102 is disposedat the far end of occlusion O as shown in FIG. 14. Once outer shaftcomponent 102 is positioned as desired, balloon 112 may be inflated asshown in FIG. 15, thus anchoring outer shaft component 102 and in turnocclusion bypassing apparatus 100 in the subintimal tract. Guidewire 170may then be proximally retracted and removed, and inner shaft component114 with needle component 130 disposed therein are concurrently loadedinto and advanced through outer shaft component 102 as shown in FIG. 16.During advancement or loading of the subassembly of inner shaftcomponent 114 and needle component 130 through outer shaft component102, angled distal tip segment 142 of needle component 130 is restrainedor held in a straightened form within reinforced intermediate portion128 of inner shaft component 114 as described above. In the alternateembodiment described above in which inner shaft component 114 does notinclude reinforced intermediate portion 128, the subassembly of theinner shaft component 114 and needle component 130 may still beconcurrently loaded into and advanced through an indwelling orpreviously placed outer shaft component 102 with the combination of theinner and outer shaft components providing sufficient rigidity tomaintain angled distal tip segment 142 of needle component 130 in astraightened form during loading and advancement of the subassembly.

Inner shaft component 114 and needle component 130 are advanced withinouter shaft component 102 until flexible distal portion 124 of innershaft component 114 distally extends from distal end 106 of outer shaftcomponent 102, as shown in FIG. 16. Although inflation of balloon 112 isdescribed as occurring prior to insertion of inner shaft component 114and needle component 130, in another embodiment hereof (not shown)inflation of balloon 112 may not occur until after positioning of theinner shaft and needle components within outer shaft component 102 solong as balloon inflation occurs prior to bending and/or rotation ofdistal portion 124 of inner shaft component 114 as described herein.

After occlusion bypassing apparatus 100 is positioned adjacent to thefar or downstream end of occlusion O as desired with balloon 112inflated and flexible distal portion 124 of inner shaft component 114distally extending from distal end 106 of outer shaft component 102,needle component 130 is distally advanced relative to inner shaftcomponent 114 in order to bend flexible distal portion 124 of innershaft component 114. More particularly, needle component 130 is distallyadvanced relative to inner shaft component 114 until angled distal tipsegment 142 is disposed within flexible distal portion 124 that extendsfrom distal end 106 of outer shaft component 102 to thereby bendflexible distal portion 124 away from the longitudinal axis of occlusionbypassing apparatus 100. When released from intermediate portion 128,needle component angled distal tip segment 142 resumes its shape memorybent or curved form and concurrently bends flexible distal portion 124of inner shaft component 114 away from longitudinal axis L_(A) ofocclusion bypassing apparatus 100 to orient distal opening 126 of innershaft component 114 towards true lumen L of vessel V. The position ofdistal portion 124 of inner shaft component 114 during bending thereofmay be monitored via marker 110 thereon. If distal opening 126 of innershaft component 114 is not oriented or pointed towards true lumen L ofvessel V, a proximal end 132 of needle component 130 may be rotated orturned by a physician. When needle component 130 is rotated, inner shaftcomponent 130 with its flexible distal portion 124 in its bent ordeployed configuration rotates therewith as described above and as shownby a directional arrow 174 in FIG. 17 to make any necessary adjustmentof the rotational position or orientation of inner shaft component 114and needle component 130 within the subintimal tract to ensure thatdistal tip 136 of needle component 130 will be deployed into a specificradial location, i.e. into the intima I, on the vessel wall. The correctrotational position or orientation of inner shaft component 114 andneedle component 130 is shown in FIG. 18, with distal opening 126 ofinner shaft component 114 oriented toward the true lumen of the vessel.During bending of distal portion 124 of inner shaft component 114 andany rotation of the inner shaft component and needle component 130,needle component distal tip 136 is disposed within inner shaft component114.

Once distal opening 126 of inner shaft component 114 is oriented towardsthe vessel true lumen as desired, needle component 130 is distallyadvanced relative to inner shaft component 114 until distal tip 136extends from or protrudes out of distal opening 126 of inner shaftcomponent 114 and penetrates the intima to gain access to the true lumenof the vessel distal to, i.e., downstream of, the CTO as shown in FIG.19. Angled distal tip segment 142 of needle component 130 still extendsthrough and bends flexible distal portion 124 of inner shaft component114 away from longitudinal axis L_(A) of occlusion bypassing apparatus100.

A second guidewire 176 may be advanced through lumen 138 of needlecomponent 130 and into the true lumen L of vessel V as shown in FIG. 20.Guidewire 176 has a relatively smaller outer diameter such as 0.014inches in order to minimize the size of needle component 130 andsubsequently minimize the size of occlusion bypassing apparatus 100.Optionally, occlusion bypassing apparatus 100 may be removed andguidewire 176 may be left in place as shown in FIG. 21, such thatguidewire 176 extends in true lumen L proximal to the CTO, through thesubintimal tract, and back into true lumen L distal to the CTO to enablethe CTO to be successfully crossed via the subintimal conduit thuscreated.

Optionally, a covered or uncovered stent may be delivered over guidewire176 and implanted within the subintimal tract to facilitate flow fromthe lumen of the vessel upstream of the CTO, through the subintimaltract and back into the lumen of the vessel downstream of the CTO. Forexample, FIG. 22 shows a distal end of a catheter 1580 having a stent1582 mounted thereon being advanced over guidewire 176 to a positionwhere a distal end 1581 of the radially collapsed stent 1582 is in truelumen L of vessel V downstream of chronic total occlusion CTO, aproximal end 1583 of stent 1582 is in true lumen L of vessel V upstreamof chronic total occlusion CTO, and a tubular body of stent 1582 extendsthrough the subintimal tract. Stent 1582 is then deployed by eitherself-expansion or balloon inflation within the subintimal reentryconduit to dilate the subintimal tract and compress the adjacent chronictotal occlusion CTO. Stent 1582 provides a scaffold which maintains thesubintimal tract in an open condition capable of carrying blooddownstream of chronic total occlusion CTO. Thereafter, guidewire 176 andcatheter 1580 may be removed from the patient, leaving stent 1582 in anexpanded configuration and creating a radially supported, subintimalblood flow channel around chronic total occlusion CTO as seen in FIG.23. In some cases, it may be desirable to enlarge the diameter of thesubintimal tract before advancing stent catheter 1580 into and throughit. Such enlargement of the subintimal tract may be accomplished bypassing a balloon dilatation catheter over guidewire 176 and inflatingthe balloon to dilate the tract, or may be any other suitable tractenlarging, dilating or de-bulking instrument that may be passed overguidewire 176.

FIGS. 24-29 illustrate an alternative method of forming a subintimaltract and positioning occlusion bypassing apparatus 100 adjacent to thedistal or downstream end of occlusion O, but it would be understood byone of ordinary skill in the art that the depicted method may be adaptedto be performed by other occlusion bypassing apparatus disclosed herein.With reference to FIG. 24, a first guidewire 1770 having a distal end1772 is transluminally advanced through the vasculature to a positionproximal or upstream of a total occlusion O within a lumen L of bloodvessel V. Similar to guidewire 170, guidewire 1770 has a relativelylarger outer diameter in order to have sufficient column strength togain access to the subintimal space of vessel V and guidewire 1770 isutilized to pierce the intima I and create a subintimal tract betweenthe intima I and the media M. A guide catheter 1890 is then tracked overguidewire 1770 and advanced such that a distal end 1892 thereof isadjacent to the distal or downstream end of occlusion O as shown in FIG.25. Guidewire 1770 may then be proximally retracted and removed, and arelatively smaller second guidewire 1976 may be loaded into and advancedthrough guide catheter 1890 as shown in FIG. 26. In an embodiment,second guidewire 1976 has a relatively smaller outer diameter such as0.014 inches.

After second guidewire 1976 is in place as desired, guide catheter 1890may be proximally retracted and removed as shown in FIG. 27, leavingonly second guidewire 1976 extending into the subintimal tract. At thispoint, occlusion bypassing apparatus 100 may be tracked over secondguidewire 1976 and advanced such that a distal end 106 is adjacent tothe distal end of occlusion O as shown in FIG. 28. In this embodiment,outer shaft component 102, inner shaft component 114, and needlecomponent 130 are concurrently advanced as an ensemble over secondguidewire 1976 rather than advancing the outer shaft component prior tothe inner shaft and needle components as described in the priorembodiment. Stated another way, inner shaft component 114 and needlecomponent 130 are loaded into outer shaft component prior to the step ofadvancing occlusion bypassing apparatus 100 over guidewire 1976. Asshown in FIG. 28, during distal advancement of occlusion bypassingapparatus 100, flexible distal portion 124 of inner shaft component 114may distally extend from distal end 106 of outer shaft component 102 aslong as angled distal tip segment 142 of needle component 130 isrestrained or held in a straightened form within inner shaft componentintermediate portion 128, if applicable, or by the interaction of outerand inner shaft components 102, 114 in embodiments in which theintermediate portion is not present. Once occlusion bypassing apparatus100 is positioned as desired, balloon 112 may be inflated as shown inFIG. 29 to anchor outer shaft component 102 in the subintimal tract.Guidewire 1976 may be proximally retracted and removed, leaving onlyocclusion bypassing apparatus 100 extending through the subintimaltract. Similarly in the alternate embodiment described above in whichinner shaft component 114 does not include intermediate portion 128, thewhole ensemble of the outer shaft component 102, inner shaft component114, and needle component 130 may be concurrently advanced over thealready in place guidewire 1976 and tracked to the lesion where balloon112 is then expanded.

Once occlusion bypassing apparatus 100 is positioned adjacent to thedistal end of occlusion O as desired with balloon 112 inflated, theremaining steps to create a subintimal conduit that bypasses theocclusion O are the same as described with respect to FIGS. 17-23. Moreparticularly, distal portion 124 of inner shaft component may be bentvia advancement of needle component 130 and the needle and inner shaftcomponents may be rotated as described above with respect to FIGS.17-18. Distal tip 136 of needle component 130 is then distally advancedto penetrate through the intima and thereafter pass into the true lumenof the vessel as described with respect to FIG. 19, and a guidewire maybe advanced through needle component 130 into the true lumen of thevessel as described with respect to FIG. 20. Optionally, a stent may bedelivered and implanted within the subintimal tract to facilitate flowfrom the lumen of the vessel proximal of the CTO, through the subintimaltract and back into the lumen of the vessel distal of the CTO asdescribed with respect to FIGS. 21-23.

In a method of forming a subintimal tract and positioning occlusionbypassing apparatus 500 adjacent to the downstream end of an occlusion,a balloon catheter of occlusion bypassing apparatus 500 comprising shaftcomponent 502 and balloon 512 is tracked over an indwelling guidewire,such as guidewire 170 shown in FIG. 13, through the subintimal tractuntil distal tip 525 of the catheter is disposed at the distal side ofthe occlusion. Balloon 512 is then inflated to anchor the ballooncatheter within the subintimal tract, as similarly shown in theembodiment of FIG. 15. Needle component 530 that is held in astraightened configuration by stylet 531 is then advanced relative tothe balloon catheter until distal tip segment 642 of the needlecomponent extends within distal shaft portion 524 of the ballooncatheter. The distal tip segment 642 of needle component 530 is thengradually and under control returned to its shape memory angledconfiguration in which it bends away from a longitudinal axis ofproximal portion 640 of the needle component 530 by distal advancementof needle component 530 relative to stylet 531 and distal shaft portion524. Stylet 531 is then removed from needle component 530 and distal tip636 of needle component 530, which extends from distal tip 525 of shaftcomponent 502, is then distally advanced and positioned to penetratethrough the intima and thereafter pass into the true lumen of thevessel. The remainder of the method of forming the subintimal tract mayproceed as described above with reference to FIGS. 20-23.

In a method of forming a subintimal tract and positioning occlusionbypassing apparatus 900 adjacent to the downstream end of an occlusion,occlusion bypassing apparatus 900 comprising shaft component 902,balloon 912 and needle component 530 is advanced over an indwellingguidewire, such as guidewire 170 shown in FIG. 13, through thesubintimal tract until distal tip 925 of the apparatus is disposed atthe distal side of the occlusion. Balloon 912 is then inflated to anchorthe apparatus within the subintimal tract, as similarly shown in theembodiment of FIG. 15. Needle component 530 is held in a straightenedform by metallic shaft segment 928 of shaft component 902 during theadvancement of occlusion bypassing apparatus 900 to the treatment site.Needle component 530 is then advanced relative to shaft component 902until at least a portion of angled distal tip segment 642 is disposedwithin distal portion 924 of shaft component 902 to thereby bend distalportion 924 away from a longitudinal axis of the occlusion bypassingapparatus. The distal tip segment 642 of needle component 530 is thenpositioned such that subsequent distal advancement relative to shaftcomponent 902 will cause the distal tip 636 to penetrate through theintima and thereafter pass into the true lumen of the vessel. Theremainder of the method of forming the subintimal tract may proceed asdescribed above with reference to FIGS. 20-23.

While various embodiments according to the present invention have beendescribed above, it should be understood that they have been presentedby way of illustration and example only, and not limitation. It will beapparent to persons skilled in the relevant art that various changes inform and detail can be made therein without departing from the spiritand scope of the invention. For example, although inner shaft component114 is primarily described to include a relatively stiff intermediateportion 128 for holding angled distal tip segment 142 of needlecomponent 130 in a straightened position during loading and/oradvancement, in another embodiment, as discussed in various placesabove, the combination or subassembly of outer shaft component 102 andproximal portion 122 of inner shaft component 114 has a sufficientstiffness to hold the angled distal tip segment of needle component in astraightened position during loading and/or advancement. As such, angleddistal tip segment 142 of needle component 130 is restrained in astraightened position when disposed within both outer shaft component102 and inner shaft component 114 but resumes its bent shape whendisposed only within flexible distal portion 124 of inner shaftcomponent 114. Thus, the breadth and scope of the present inventionshould not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the appendedclaims and their equivalents. It will also be understood that eachfeature of each embodiment discussed herein, and of each reference citedherein, can be used in combination with the features of any otherembodiment.

What is claimed is:
 1. A method for bypassing an occlusion in a bloodvessel having a subintimal tract formed in a wall of the vessel adjacentto the occlusion, said method comprising the steps of: advancing aguidewire through the subintimal tract from a proximal side of theocclusion to a position where a distal end of the guidewire ispositioned in the subintimal tract on a distal side of the occlusion;advancing a balloon catheter through the subintimal tract over theguidewire until a distal portion of the catheter is disposed at thedistal side of the occlusion; inflating a balloon of the ballooncatheter to anchor the balloon catheter within the subintimal tract;advancing a needle component in a straightened configuration relative tothe balloon catheter until a distal tip segment of the needle componentextends from a distal end of the balloon catheter; and permitting theneedle component to return to an angled configuration in which thedistal tip segment bends away from a longitudinal axis of a proximalportion of the needle component, wherein at least the distal tip segmentof the needle component has a shape memory to return the needlecomponent to the angled configuration.
 2. The method of claim 1, whereinduring the step of advancing the needle component relative to theballoon catheter the needle component is held in the straightenedconfiguration by an elongate stylet that extends through a lumen of theneedle component.
 3. The method of claim 2, wherein the step ofpermitting the needle component to return to the angled configurationincludes distally advancing the needle component relative to theelongate stylet until the distal tip segment bends.
 4. The method ofclaim 1, wherein an elongate shaft component is slidably disposed withinthe balloon catheter and the elongate shaft component includes a lumenwithin which the needle component is slidably disposed.
 5. The method ofclaim 4, further comprising: loading the needle component within theshaft component prior to the step of advancing the needle componentrelative to the balloon catheter such that the needle component is heldin the straightened configuration by a reinforced segment of the shaftcomponent.
 6. The method of claim 5, further comprising prior to thestep of permitting the needle component to return to the angledconfiguration: advancing the needle component relative to the shaftcomponent until the distal tip segment of the needle component isdisposed within a distal portion of the shaft component that extendsfrom the distal end of the balloon catheter such that during the step ofpermitting the needle component to return to the angled configurationthe distal portion of the shaft component is bent by the distal tipsegment of the needle component.
 7. The method of claim 6, furthercomprising the steps of: rotating the shaft component with the distalportion in its bent configuration until a distal opening of the shaftcomponent is oriented toward the true lumen of the vessel; andcontinuing the advancement of the needle component relative to the shaftcomponent until a distal tip of the needle component extends from thedistal opening of the shaft component and penetrates the wall of thevessel to gain access to the true lumen of the vessel.
 8. The method ofclaim 7, wherein the balloon catheter includes an elongate outer shaftcomponent on which the balloon is mounted and within which the shaftcomponent is slidably disposed.
 9. A method for bypassing an occlusionin a blood vessel having a subintimal tract formed in a wall of thevessel adjacent to the occlusion, said method comprising the steps of:advancing a guidewire through the subintimal tract from a proximal sideof the occlusion to a position where a distal end of the guidewire ispositioned in the subintimal tract on a distal side of the occlusion;advancing an outer shaft component of an occlusion bypassing apparatusover the guidewire until a distal portion of the outer shaft componentis disposed at the far side of the occlusion; loading an inner shaftcomponent and a needle component of the occlusion bypassing apparatuswithin the outer shaft component until a distal portion of the innershaft component is disposed within the distal portion of the outer shaftcomponent, wherein the needle component is slidably disposed within theinner shaft component; inflating a balloon of the occlusion bypassingapparatus to anchor the occlusion bypassing apparatus within thesubintimal tract; and advancing the needle component of the occlusionbypassing apparatus relative to the inner shaft component until at leasta portion of an angled distal tip segment of the needle component isdisposed within the distal portion of the inner shaft component thatextends from a distal end of the outer shaft component to thereby bendthe distal portion of the inner shaft component away from a longitudinalaxis of the occlusion bypassing apparatus.
 10. The method of claim 9,further comprising the steps of: rotating the inner shaft component withthe distal portion in its bent configuration until a distal opening ofthe inner shaft component is oriented toward the true lumen of thevessel; and continuing the advancement of the needle component relativeto the inner shaft component until a distal tip of the needle componentextends from the distal opening of the inner shaft component andpenetrates the wall of the vessel to gain access to the true lumen ofthe vessel.
 11. The method of claim 9, wherein the step of inflating theballoon to anchor the occlusion bypassing apparatus is performed priorto the step of loading the inner shaft component and the needlecomponent within the outer shaft component.
 12. The method of claim 9,wherein during the step of advancing the guidewire through thesubintimal tract, the guidewire is advanced through a prior placed guidecatheter that extends within the subintimal tract.
 13. The method ofclaim 12, further comprising the step of: removing the guide catheterprior to the step of advancing the outer shaft component through thesubintimal tract over the guidewire.
 14. The method of claim 9, whereinthe distal portion of the inner shaft component is bent at an acuteangle with respect to the longitudinal axis of the apparatus.
 15. Themethod of claim 9, wherein the distal portion and a proximal portion ofthe inner shaft component are of a polymeric material and a metallicshaft segment is disposed between the distal portion and the proximalportion of the inner shaft component.
 16. The method of claim 15,wherein during the step of loading the inner shaft component and theneedle component within the outer shaft component the angled distal tipsegment of the needle component is held in a straightened form by themetallic shaft segment of the inner shaft component.
 17. The method ofclaim 9, wherein the step of loading the inner shaft component and theneedle component within the outer shaft component is performed prior tothe step of advancing the outer shaft component over the guidewire. 18.A method for bypassing an occlusion in a blood vessel having asubintimal tract formed in a wall of the vessel adjacent to theocclusion, said method comprising the steps of: advancing a guidewirethrough the subintimal tract from a proximal side of the occlusion to aposition where a distal end of the guidewire is positioned in thesubintimal tract on a distal side of the occlusion; advancing anocclusion bypassing apparatus having a shaft component and a needlecomponent through the subintimal tract over the guidewire until a distalend of the occlusion bypassing apparatus is disposed at the distal sideof the occlusion, wherein the needle component is slidably disposedwithin the shaft component and defines a lumen through which theguidewire extends; inflating a balloon of the occlusion bypassingapparatus to anchor the occlusion bypassing apparatus within thesubintimal tract; and advancing the needle component relative to theshaft component until at least a portion of an angled distal tip segmentof the needle component is disposed within a distal portion of the shaftcomponent to thereby bend the distal portion of the inner shaftcomponent away from a longitudinal axis of the occlusion bypassingapparatus.
 19. The method of claim 18, further comprising: continuingthe advancement of the needle component relative to the shaft componentuntil a distal tip of the needle component extends from a distal openingof the shaft component and penetrates the wall of the vessel to gainaccess to the true lumen of the vessel.
 20. The method of claim 18,wherein the angled distal tip segment of the needle component is held ina straightened form by a metallic shaft segment of the shaft componentduring the step of advancing the occlusion bypassing apparatus.